The present invention relates to bulk containers for storing and transporting large volumes of fluid. Specifically, the present invention relates to a one-piece bulk container bottom that will drain completely without being tipped, and that has the strength and durability to endure the stresses associated with transporting, repeated loading and rough handling of the container.
Bulk containers are used to store and transport large volumes (hundreds of gallons) of fluid. The fluids stored and transported may be hazardous, corrosive or otherwise difficult to handle. Each time the container is drained, it is important to completely remove what residual fluid has clung to the features of the container before the container is reused. The size and weight of intermediate bulk containers make tipping or shaking the container to facilitate complete drainage extremely awkward. Ideally the container geometry maximizes the drainage of those fluids contained within without requiring the container to be tipped or moved. The more completely a container drains, the less time is spent cleaning the container between uses.
Because these containers are large, awkward and weigh thousands of pounds when full, they are typically moved and handled using heavy machinery such as a forklift. Such handling cannot be described as delicate. As a result, bulk containers must be able to stand up to an occasional offensive touching from the prong of a forklift without diminishing their drainage efficiency. Container bottoms ideally have few features which hang below the container floor and which would interfere with forklift handling. Containers that do not have these features are both easier and safer to handle.
Prior container bottoms that were constructed of two or more parts welded together had an increased chance of cracking at the welded seams because of cyclic stresses the container is exposed to over time. Similarly, any creased or sharply angled portions of a container bottom are prone to failure due to cyclic stresses.
Prior bulk containers with flat bottoms had a tendency to sag after numerous loadings or under the weight of a full load of fluid. Sagging made these containers prone to failure and made them difficult to drain completely.
Some prior containers had raised centers and discrete fluid pathways, formed canals or cut channels which directed fluids to a drainage opening and thereby were intended to improve the drainage characteristics of the container. Such drainage pathways were typically formed below the elevation of a container bottom and therefore prone to be deformed by rough handling of the container by forklift. Sharp edges and creases associated with these features in prior container bottoms allow fluids contained therein to cling to the container bottom rather than to drain through the drainage opening. Fluid left behind after the container is drained increases the time it takes to clean and prepare the container for its next use.